This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In order to improve our diagnostic pathology capabilities, we systematically evaluate commercially available antibodies directed against human cells/tissues and infectious agents for application in the nonhuman primate species housed at the NEPRC. Antibodies are selected for potential applications in diagnostic and/or experimental pathology, and for reactivity in either snap-frozen or formalin-fixed, paraffin-embedded tissues. In addition, the Division of Comparative Pathology receives multiple requests each year to test antibodies and develop IHC protocols for investigators in our Division, other NEPRC Divisions, and collaborating investigators. Thus, research and development to identify antibodies for immunohistochemistry in nonhuman primates is an important activity of the Molecular Pathology Core, and has contributed to the development of a diverse repertoire of IHC antibodies that work consistently in macaque tissue. In one study we were able to identify 21 of 21 antigens in 4 macaque species and 17 of 21 in New World monkeys, and during 2005, we developed immunohistochemistry protocols for 21 new antibodies that were cross-reactive in monkey tissues. The Division of Comparative Pathology also trains investigators, technicians, postdoctoral fellows and graduate students in immunohistochemistry methods. AIDS related.